In medical instruments each provided with a rod-shaped grasp portion at its base end and a functional portion such as a knife, mirror, hook, retractor and dilator used in medical practice at its front end, it has conventionally been general that the grasp portion and the functional portion are arranged substantially linearly.
FIGS. 12 to 14 show one example of such conventional medical instruments. FIG. 12 is a schematic view showing an example of the conventional medical knife, and FIG. 13 is a schematic view showing an example of the conventional medical mirror.
A medical knife 101 shown in FIG. 12 has a rod-shaped grasp portion 102 at its base end, while being provided with a knife body 104 as a functional portion at its front end. Further, a medical mirror 201 as shown in FIG. 13 has a rod-shaped grasp portion 202 at its base end, while being provided with a mirror body 204 as a functional portion at its front end. As shown in the figures, the grasp portions 102 and 202 and the functional portions 104 and 204 are arranged substantially in the straight line fixedly, respectively.
However, for example, in heart coronary-artery bypass surgery and the like, from the relationship between the position of a blood vessel to cut and an insertion angle of the medical knife, the conventional medical knife as shown in FIG. 12 sometimes hides the knife front end in the hand of the operator, and therefore, in such a medical knife 101 in which the grasp portion 102 and knife body 104 are arranged in the straight line as described above, there is a problem that the knife 101 is hard to see and use in cutting.
Then, such medical knives have previously been commercially available that a removable knife body can be disposed at an arbitrary angle with respect to the grasp portion (for example, Patent Document 1). FIG. 14 shows a conventional medical knife. The medical knife 301 is comprised of a grasp portion 302, and a knife body (functional portion) 304 in the shape of a “C”. Since the knife body 304 is bent in the shape of a “C”, while a connection portion between the grasp portion 302 and the knife body 304 is bent, it is possible to attach the blade at a certain angle with respect to the grasp portion 302. Prepared as the knife body 304 is a plurality of kinds with different bending angles, and as necessary, the knife body 304 with an arbitrary angle is attached and used.
Meanwhile, the medical mirror 201 is used to visually identify an area such as a deep narrow operation site and the inside of the oral cavity that are normally hard to see, and conventionally, as shown in FIG. 13, by attaching the mirror body 204 at an angle with respect to the grasp portion 202, an observation object is made easy to see.
In the case of the above-mentioned conventional medical knife 301 as shown in FIG. 14, since the bending angle of the knife body 304 is beforehand set, there is a problem that the angle of the knife body 304 can only be changed stepwise. In other words, versatility of the change angle of the knife body 304 is low, and it is not possible to set a delicate angle corresponding to the situation. Further, in the case of desiring to change to a different angle during the treatment, there is a problem of preparing the new medical knife 301 again, or of removing the knife body 304 from the grasp portion 302 to replace with the knife body 304 with a different bending angle.
Therefore, medical instruments deformable to a bent state and changeable in the position have been known using shape-memory alloys in a part of some middle portion of a shaft portion formed between the functional portion and the grasp portion (for example, Patent Document 2).